In a 3rd Generation Partnership Project (3GPP) system, the policy and charging functions are implemented in a PCC architecture. The PCC architecture implements two functions: policy control and charging.
The policy control function includes six aspects: (1) monitoring the process of negotiating the service parameters (such as Quality of Service (QoS) parameter) of the user; (2) authorizing the network bearer resources used by the service according to the obtained service information; (3) controlling the pass of the service flow on the data bearer plane in real time; (4) notifying the change of the service plane to the data bearer plane; (5) notifying the change of the data bearer plane to the service plane; and (6) performing policy control based on the subscription profile of the user.
The charging function includes three aspects: (1) formulating charging rule(s) according to the service information, bearer information and subscription profile; (2) performing correlation between the service-plane charging data and the bearer-plane charging data; and (3) performing credit control in a dynamic charging mode.
FIG. 1 shows a structure of a PCC architecture in the prior art. As shown in FIG. 1, the policy control function of the existing PCC architecture involves these logical entities: Application Function (AF) entity, Policy and Charging Rules Function (PCRF) entity, Policy and Charging Enforcement Function (PCEF) entity, and Subscription Profile Repository (SPR) entity. The charging function of the existing PCC architecture involves not only the AF entity, the PCRF entity, the PCEF entity, and the SPR entity, but also other logical entities such as an Online Charging System (OCS) entity and an Offline Charging System (OFCS) entity.
The functions of the entities are elaborated below.
The AF entity is configured to provide a service application access point. The network resources used by such service applications need dynamic policy control. In the parameter negotiation on the service plane, the AF entity transfers the relevant service information to the PCRF entity. If such service information is consistent with the policy rule(s) defined on the PCRF entity, the PCRF entity accepts the negotiated service parameters. Otherwise, the PCRF entity rejects the negotiation, and may give a feedback which carries the service parameters acceptable to the PCRF entity. Afterward, the AF entity may return such parameters to the user. The AF entity is interfaced with the PCRF entity through an Rx interface.
The PCRF entity is a core of the PCC system, and is responsible for formulating the policy decision and charging rule(s). The PCRF entity provides network control rule(s) based on the service data flow. The network control includes: data flow detection, gating, QoS control, and flow-based charging control. The PCRF entity sends the formulated policy and charging rule(s) to the PCEF entity for executing, and ensures that such rule(s) are consistent with the subscription profile of the user. The PCRF entity formulates the policy and charging rule(s) according to the information such as the service-related information obtained from the AF entity, subscription profile-related information obtained from the SPR entity, and the bearer network-related information obtained from the PCEF entity.
On the bearer plane, the PCEF entity may execute the policy and charging rule(s) formulated by the PCRF entity. The PCRF entity may deliver trigger events to the PCEF entity. The PCEF entity requests PCC rule(s) from the PCRF entity only when such a trigger event occurs. The PCEF entity detects the service data flows according to a traffic filter in the rule(s) sent by the PCRF entity, and performs the policy and charging control formulated by the PCRF entity to such service flows. When creating a bearer, the PCEF entity performs QoS authorization according to the rule(s) sent by the PCRF entity, and performs a gating operation according to the instruction of the AF entity. The PCEF entity executes the service flow charging operation according to the charging rule(s) sent by the PCRF entity. Such a charging operation may be online charging or offline charging. For online charging, the PCEF entity works together with the OCS entity to perform credit management; for offline charging, the PCEF entity exchanges the relevant charging information with the OFCS entity. The PCEF entity is interfaced with the PCRF entity through a Gx interface, interfaced with the OCS entity through a Gy interface, and interfaced with the OFCS entity through a Gz interface. The PCEF entity is generally located in a Gateway (GW) of the network.
The SPR entity stores the user subscription profile related to policy control and charging, for example, information about services available to the user, information about the QoS available to the user service, user subscription profile related to charging, and group type of the user. By using the information stored in the SPR entity, the PCRF entity may perform policy control and charging operations based on the user subscription profile. The SPR entity is interfaced with the PCRF entity through an Sp interface.
With evolution of the mobile communication network, a new PCC architecture is currently put forward. FIG. 2 shows a structure of a new PCC architecture. In the new PCC architecture, the PCEF is divided into a PCEFa entity and a PCEFb entity. The PCEFa entity and the PCEFb entity may be configured respectively into an Access Gateway (A-GW) and an Evolved Packet System (EPS) Home Agent (HA). No bearer exists between the A-GW and the EPS HA. Therefore, the bearer plane-related functions (for example, bearer binding function) of the PCEF entity are configured in the PCEFa entity of the A-GW. An SGi interface exists between the EPS HA and a Packet Data Network (PDN). Therefore, the functions such as the charging function and the gating function are configured in the PCEFb entity of the EPS HA. The A-GW may be a serving GW or a PDN GW, or other core network entity, and the EPS HA may be a PDN GW or other core network entity.